This invention relates, generally, to molded products made from thermo plastic materials, and specifically, to composite railroad ties and methods for making same. The invention relates more specifically to new and improved railroad ties which will last longer in hot, humid environments and to methods for making such railroad ties.
It is well known to make railroad ties from thermoplastic materials, for example, as described in U.S. Pat. No. 5,799,870 to John C. Bayer.
It is also known to make railway ties from sand and recycled thermoplastic containers, for example, as described in U.S. Pat. No. 5,055,350 to Charles W. Neefe.
It is also well known to make railroad ties from recycled tire fragments, for example as described in U.S. Pat. No. 5,238,734.
Moreover, it is well known to make porous flexible pipes from thermoplastic materials and thermoset materials, for example, as described in U.S. Pat. No. 5,366,365 to Henry W. Sullivan, et al.
It is also well known to make sheet products from thermoplastic material combined with granular scrap material, for example, old automobile tires, as described in U.S. Pat. No. 4,970,043 to Rosetta C. Doan, as well as in U.S. Pat. No. 5,733,943, also to Rosetta C. Doan.
Moreover it is known to make railroad ties from combinations of polymeric components combined with a rubbery polymeric component obtained from disposed tires, such as is described in U.S. Pat. No. 5,886,078 to Henry W. Sullivan, et al.
In addition, it is known to make elongated cylindrical molds having an internal sliding piston which allows the molten plastic to be introduced into the mold which produces an elongated plastic body having the tube imbedded therein.
The prior art also includes U.S. Pat. No. 4,824,627 to Floyd V. Hammer, and U.S. Pat. No. 4,191,522 to James E. Turner which relate to various molded plastic products and extruding machines for manufacturing extruded products.
The prior art also includes U.S. Pat. Nos. 5,507,473 to Floyd V. Hammer et al; 4,028,288 to James E. Turner and 5,951,712 to Jerome Campbell.
A common element running through most if not all of the above referenced prior art patents is the use of using shredded rubber products in the finished product, such as used automobile and truck tires.
However, the prior art taken individually and in combination fails to provide the solution to manufacturing processes for making reliable railroad ties, or to the composition of the railroad ties themselves.
Specifically, the prior art fails to provide methods or apparatus which have the time efficiencies necessary to manufacture and supply railroad ties to the railroad industry.
It is therefore the primary object of the present invention, generally, to provide new and improved molded products made from thermoplastic materials, and specifically, to provide new and improved rail road ties, and to methods for making the same.